This invention relates to an osteoinduction substance for use mainly in dental treatment to accelerate creation of a new bone, to a method of manufacturing the osteoinduction substance, and to a bone filling material including the osteoinduction substance.
In dental treatment, attempts have been made of accelerating the reproduction of a bone by artificially implanting an osteoinduction substance in a resected site of a jaw bone.
In Japanese Unexamined Patent Publication No. 24994/1994, the present inventor proposes his earlier invention directed to such an osteoinduction substance which is extracted from animal bones and which contains MgCO.sub.3, Ca.sub.2 SiO.sub.4, CaO, and Ca(OH).sub.2.
The osteoinduction substance according to the above-mentioned earlier invention is artificially implanted in a resected site of a jaw bone to accelerate reproduction of a bone.
In the earlier invention, a small amount of the osteoinduction substance is mixed with chitosan sol and hydroxyapatite to form a bone filling material. The bone filling material can be formed not only into a hardenable type but also into a sheet type.
In order to manufacture the osteoinduction substance, the animal bones are at first dipped in acidic aqueous solution, rinsed, and subjected to liming. Then, the animal bones are again rinsed to remove water-soluble substances, keratin, and fat therefrom. As a consequence, a starting material is obtained. Subsequently, the starting material is neutralized by the use of acid, rinsed, and thereafter heated to obtain an extract. The extract is filtered to collect mother liquor. The mother liquor is subjected to vacuum condensation, cooled, and solidified into a solidified material. The solidified material is cut and dehydrated to obtain gelatin. The gelatin is heated at a high temperature into the osteoinduction substance. The osteoinduction substance thus obtained is effective in creation of a new bone when a small amount of the osteoinduction substance is added to apatite which is known as a bone filling material.
When the osteoinduction substance is mixed with chitosan sol, it is possible to manufacture the bone filling material of a sheet type containing the osteoinduction substance because the osteoinduction substance has an ability of gelatinizing the chitosan sol. It has also been confirmed that, by the use of the mixture of the osteoinduction substance and chitosan sol, the contents of CaO and ZnO can be reduced as compared with a neutral bone filling material of a hardenable type.
To obtain the osteoinduction substance, the gelatin is heated at a temperature between 600.degree. C. and 1000.degree. C. for one to two hours. During this high-temperature process, an offensive odor or malodor is inevitably emitted from the gelatin and brings about environmental pollution. In this connection, the osteoinduction substance must be manufactured by the use of a special heating apparatus capable of dealing with such offensive odor.
In addition, the gelatin is heated in a furnace to a high temperature ranging between 600.degree. C. and 1000.degree.C. Thus, the above-mentioned method is disadvantageous in view of heat economy.